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A method for improving water flux of composite forward osmosis membrane

A forward osmosis membrane and water flux technology, applied in the field of membrane separation, can solve the problems of low water flux of forward osmosis membrane, lack of large finger-shaped pore structure, large tortuosity of finger-shaped pore structure, etc. Quantity, reducing the phenomenon of internal concentration polarization, the effect of simple method

Active Publication Date: 2021-11-05
OCEAN UNIV OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the base membrane of the composite forward osmosis membrane is generally prepared by the phase inversion method, and the base membrane forms more sponge-like pores during the phase inversion process, lacking large finger-like pore structures, or finger-like pore structures. The tortuosity is large, so the water flux of the prepared forward osmosis membrane is low

Method used

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  • A method for improving water flux of composite forward osmosis membrane
  • A method for improving water flux of composite forward osmosis membrane
  • A method for improving water flux of composite forward osmosis membrane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] Example 1: basement membrane soaked in 30% DMAc for 1 hr

[0056] Preparation method: Soak the basement membrane prepared in step (3) of Comparative Example 1 with a volume ratio of 30% DMAc aqueous solution for 1 hour, take it out, and fully wash it in deionized water. The rest of the steps are the same as in Comparative Example 1. Wash thoroughly with water and store in 1% sodium bisulfite solution.

[0057] Performance: With 1M NaCl and deionized water as the draw liquid and raw material liquid, the water flux of the forward osmosis membrane is 12.60±0.50LMH, the reverse salt flux is 3.21±0.50gML, and the brine ratio is 0.25g / L.

[0058] Structure: The membrane is composed of a porous support layer and a dense separation layer. The thickness of the spongy layer on the support layer decreases, but the change is not great.

Embodiment 2

[0059] Embodiment 2: The basement membrane is soaked in 50%DMF for 30min

[0060] Preparation method: Soak the base membrane prepared in step (3) of Comparative Example 1 in 50% DMF aqueous solution for 30 minutes, take it out, and wash it fully in deionized water. Rinse thoroughly with deionized water and store in 1% sodium bisulfite solution.

[0061] Performance: With 1M NaCl and deionized water as the draw solution and raw material solution, the water flux of the forward osmosis membrane is 14.90±0.61LMH, the reverse salt flux is 3.61±1.01gMH, and the brine ratio is 0.24g / L.

[0062] Structure: The membrane is composed of a porous support layer and a dense separation layer. The large finger-like pore structure in the membrane increases, and the thickness of the spongy layer in the support layer becomes smaller.

Embodiment 3

[0063] Embodiment 3: basement film soaks 1hr in 50%DMAc

[0064] Preparation method: Soak the base membrane prepared in step (3) of Comparative Example 1 in 50% DMAc aqueous solution for 1 hour, take it out, and wash it fully in deionized water. Rinse thoroughly with deionized water and store in 1% sodium bisulfite solution.

[0065] Performance: With 1M NaCl and deionized water as the draw liquid and raw material liquid, the water flux of the forward osmosis membrane is 16.20±0.72LMH, the reverse salt flux is 3.69±1.01gMH, and the brine ratio is 0.23g / L.

[0066] Structure: The membrane is composed of a porous support layer and a dense separation layer. The thickness of the spongy layer in the support layer becomes smaller, and the large finger-like pore structure in the membrane increases.

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Abstract

The invention discloses a method for improving the water flux of a composite forward osmosis membrane, which comprises the following steps: (1) putting the base membrane of the forward osmosis membrane into an aqueous solution of an organic solvent for soaking treatment; (2) soaking the base membrane of the forward osmosis membrane After the base membrane is taken out, it is cleaned with water; (3) A separation layer is prepared on the base membrane through interfacial polymerization, thereby obtaining a high-flux polyamide composite forward osmosis membrane. In the present invention, the pore wall of the base film is thinned by immersion in an organic solvent, the pore structure changes, and the tortuosity of the film pores becomes smaller. At the same time, the porosity of the base film is increased, and the number of large finger-shaped pores is also increased, thereby reducing the thickness of the film. The structural parameters of the forward osmosis membrane reduce the internal concentration polarization phenomenon of the forward osmosis membrane, and finally improve the water flux of the composite forward osmosis membrane. The method of the invention is simple, easy to implement, and is especially suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to a method for preparing a forward osmosis (FO) membrane, in particular to a method for improving the water flux of a composite forward osmosis membrane, and belongs to the technical field of membrane separation. Background technique [0002] The forward osmosis (FO) process is driven by the osmotic pressure difference between the draw solution and the raw material solution, and water automatically diffuses from the raw water side with a high water chemical potential to the draw solution with a low water chemical potential through a selective permeable membrane. side process, in which no external pressure and energy are required. Therefore, compared with processes such as reverse osmosis (RO), the forward osmosis process has the advantages of low energy consumption, high water recovery rate, less fouling of the membrane, and operation under normal temperature and pressure. It has been used in food, pharmacy, energy and other fiel...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D69/00
CPCB01D67/0088C02F1/445
Inventor 王铎孙娜
Owner OCEAN UNIV OF CHINA
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